Labour has called for an inquiry into Andrew Mitchell's foul-mouthed tirade at
armed officers, as police groups refuse to accept a second apology.

This morning, Mr Mitchell said sorry for shouting at police officers in his first televised appearance since he was accused of calling them "plebs" and "morons".

He admitted losing his temper after a "long and extremely frustrating day" and said he did not use such abusive language. However, he declined to explain exactly what happened during the row about whether he could cycle his bike through the main gates of Downing Street.

Labour MP Bill Esterson has written to the parliamentary commissioner for standards, Sir John Lyon, demanding he investigate whether Mr Mitchell broke the MPs' code of conduct.

Mr Esterson said: "David Cameron is showing himself too weak to sort this out. He is refusing to detail what happened and refusing to ask for the Cabinet Secretary to investigate.

"It is now about whether a Government minister can get away with questioning the integrity of the police.

"The parliamentary commissioner for standards must step in to provide answers as fast as possible."

The Conservatives have been hoping the second apology would "draw a line" under the incident but this morning the furore showed signs of escalating.

Pressure is now growing on Mr Mitchell to explain what exactly he said. John Tully, chairman of the Metropolitan Police Federation, said there needs to be a "full and frank inquiry" to establish who is telling the truth.

"It is not the words, police officers are quite thick skinned, what infuriates me here is that a minister is saying police officers are liars," he said. "There is a clear difference of opinion, and we need to establish what happened."

Nick Clegg, the deputy Prime Minister, also waded into the debate by saying Mr Mitchell should give a full explanation.

"I think, therefore, it's really important that Andrew Mitchell explains fully and in detail his version of events," he told the BBC

Mr Mitchell, the Chief Whip, has now said he hopes to "draw a line" under the incident, after the police officer concerned accepted his personal apology.

"I want first of all to reiterate the apology I made last week after the incident on Wednesday night," he said this morning.

“It had been the end of a long and extremely frustrating day, not that it is any excuse at all for what happened.

“I did not show the police the amount of respect I should have done. We should all respect the police; they do an incredibly difficult job.

“I have apologised to the police. I have apologised to the police officer involved on the gate and he has accepted my apology and I hope very much we can draw a line under it there.

“I am very clear about what I said and what I did not say. I want to make it absolutely clear that I did not use the words that have been attributed to me.

"I'm now going to go in and get on with my work."

Mr Mitchell delivered his short statement on his way to work, after stepping out of a modest VW car which pulled over in a bus lane.

His words follow newspaper reports detailing the official police report into exchange, which appear to show he did use the contentious word "plebs".

The document, outlined in The Sun newspaper today, was written shortly after the incident and is said to be supported by the verbatim notes of at least two officers.

Prime Minister David Cameron has said: "What Andrew Mitchell said and what he did was not appropriate, it was wrong and it's right he's apologised.”